The Facts About 250 Gallon Fish Tank Dimensions

Last Updated on January 13, 2022 by Fabiola L.

So you feel ready to take on aquaponics but are stuck on deciding the fish tank size that fits your needs.  There are many size choices, and this article will tell you all you need to know about 250 Gallon Fish Tank Dimensions and its functions.  

It is important to determine the goals of your aquaponics system before making an important decision like tank size.  Tank size impacts the amount of fish you can raise, the type of pump you need, sump tank size, the kind of space you need for your setup, and more! 

If you are considering using a tank as large as 250 gallons, your project is quite large.   

Read on to know if it’s the right choice for you.

Fish Tank Size Basics

Sizes generally run from 50-gallon tanks up to 250 gallons.  Be careful to note that fish tank volume dimensions are measured from the inside walls of the fish tank,  NOT the outside.   It is important for you to bring a measuring tape when purchasing your tank in order to confirm that you are receiving the right dimensions listed on the box.

Keep in mind that your tank will not only be filled with water.  Everything inside your tanks such as the fish, plants, and rocks, displace the water.  This lowers the exact volume of water that can go into it.

In terms of water volume, there are two measurements to pay attention to: “Theoretical Volume” (before water is displaced) and “Realistic Volume” (after everything is inside your tank).

The actual weight of the water and tank will depend on a few factors.  First, if you are using saltwater or freshwater (saltwater weighs more).  Second off, the contents of the tank will increase the weight. 

On average, a gallon of freshwater weighs in at 8.3 Pounds and a gallon of saltwater 8.5 Pounds.  We will use this measurement to calculate the exact weight of a 250-gallon tank in the next section.  

Fish Tank Size Basics

Learn  more about: How To Fix Hard Water In Fish Tank

250 Gallon Fish Tank Specs

The Length, Width, and Height of a 250 Gallon Tank is 96 inches x 18 inches x 31 inches (2400mm x 450mm x 787mm).  An empty tank without water weighs around 385 Pounds.  Only Freshwater, filled to the top, adds an additional 2075 Pounds.

So without any plants, rocks, or fish, you are getting a minimum weight of 2460 pounds!  This is extremely heavy- you will need a permanent spot for your tank that will never need to be moved.  

Make sure your floor will be able to hold that amount of weight.  It may be necessary to add additional supports underneath the tank frame to ensure it is adequately supported. 

This large amount of water also determines the type of pump required for operation. 

The non-profit organization World Water Reserve states as a general rule of thumb, “your water pump should be able to circulate the entire system within two hours”  Basically that means for a 250-gallon tank, you want to make sure the pump can move 250 Gallons per hour.  So you need to get a pump that has a minimum of 250 GPH (gallons per hour).   

 Please note these metrics depend on how often you plan to flood your grow beds.  

Benefits Of A Large Tank

The larger the tank, the happier your fish will be.  Remember, in the natural environment fish have huge bodies of water to swim around in!! If you can afford it, having a large tank will keep your fish healthier and give them lots of space to swim around in.  

This also makes it easier to keep clean and will lower the times you need to change and clean the water.  This is simply because there is a larger volume to work with.  If you are new to aquaponics, using a 250-gallon tank will raise your chances of success.    

Another obvious benefit is that the larger the tank is, the more fish you can raise.  In general, 1 pound of fish can fit into 5-7 gallons of water.  So if your tank is 250 gallons, it can fit around 50 pounds of fish.  

That is a lot of good fertilizer for your plants and tasty food (if you eat fish!).  The fish species you work with will determine the exact amount of fish that can go in your tank.  As a reference, a 9 month grown tilapia weighs about 1 pound on average.  

However, with the right conditions, they could grow up to 5 pounds! So be sure to consider your fish species when determining how many to stock your pool with.   

This large size of the tank will also enable you to provide nutrients and water for more grow beds.  

 In order to calculate the amount of grow space, you can have,  use the rule that 1 pound of fish provides for about 1 square foot of garden space (12 inches deep beds).  This means that a 250-gallon tank can easily provide enough water and nutrients for about 50 square feet of garden space.  

Summing It Up

If you are wanting to grow decent amounts of food in both plant and fish form, a 250-gallon tank is an excellent starting point.  However, using this tank size requires a lot of space that may not be readily available.  

If you are a hobbyist aquaponics person, it makes more sense to go with a smaller tank size like 50 gallons or 100 gallons.  The small size saves you money on supplies. 

But if you want to have a more serious aquaponics system, it’s highly recommended that you start off with a 250-gallon tank (1000 liters).  Don’t be intimidated with the large water amount, its actually easier to work with higher volumes of water because it’s more forgiving.  

Aquaponics is all about understanding the principles.  Once you accomplish that, it’s easy to scale your system up or down.  Good luck and enjoy the process! 

Please feel free to comment and ask questions below!

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